1) An MD-83 would burn roughly 13% more fuel at Long Range Crz at FL 250 than at Long Range Crz at FL 310. (sorry, don't have a chart for FL 200 handy). For a distance of 150 NM/20 min this would be about 300 lbs difference, less than for an average taxi. Other types that I have flown would show similar percentages. Since most airlines carry a contingency fuel of 5% the total trip fuel, this would pose little problem.
2) Some computer flight plans take into account intermediate level-offs caused by ATC handovers. If not and I anticipated it I would add -at least- that amount as extra fuel, although this is supposed to be covered by the route reserve (contingency).
Last edited by TE RANGI; 7th May 2002 at 08:12.